This invention relates to flat panel displays and more specifically to positioning of getters in field emission devices ("FEDs"), examples of which are seen in U.S. Pat. Nos. 3,665,241; 3,755,704; 3,812,559; and 5,064,396, all of which are incorporated herein by reference.
In the use of FEDs, where there is a vacuum between and electron emitter and an anode, gas molecules are released which can cause operational problems (for example, see U.S. Pat. Nos. 5,223,766; and 4,743,797, incorporated herein by reference). Thus, a material commonly known as a "getter" is inserted in the vacuum space, for example on the side of the area between the emitter on the cathode and the phosphor on the anode. Common getter materials include titanium and other highly reactive materials. These materials react with the molecules generated during operation, preventing the molecules from causing voltage breakdown within the device.
However, the placement of the getter on the side increases the width of the display. Further, activation of the getter by heating or passing a current through the getter causes evaporation or sublimation of the getter material. Since the getter material is, at least in some cases, conductive, deposition of the material on the cathode or grid of the FED could cause shorts or otherwise adversely effect the operation of the device. Therefore, various bulky methods, such as shields, have been devised to isolate the getter from the cathode and grid. Therefore, during the evaporation or sublimation, the getter material will deposit on non-active elements in the vacuum space. Unfortunately, however, this results in the getter being placed in areas remote from the very location where molecules are generated--namely, the cathode, grid and anode.
Therefore, there is a need for a method and device for placement of a getter in an FED wherein the activation of the getter does not cause a deposit of conductive material on the grid or cathode, wherein the getter is near the locations where molecules are generated, and without the extra space and bulk used in previous devices and methods.
It is an object of the present invention to fulfill those needs.